Gas chromatography (GC) is used to analyze and detect the presence of many different substances in a gaseous or vaporized sample. The function of a gas chromatograph is to separate the components of a chemical sample and detect the presence and frequently the quantity of those components. The separation is frequently accomplished using a capillary column. This column is essentially a piece of fused silica tubing with a coating on the inside that interacts with the sample to separate the components. The dimensions of this column vary, but typical inside diameters range from 100 microns to 530 microns. Typical lengths range from 5 meters to 60 meters.
If the user is analyzing a sample that contains relatively non-volatile components, those components will deposit on the inner walls of the column, contaminating the column and possibly degrading its performance. If enough degradation occurs after repeated analyses, the user will have to take action to mitigate if not eliminate the impact of contaminants in the column.
Known methods to address the ill-effects of contaminants in the GC system include repeatedly trimming the contaminated part of the column and/or replacing the column. Alternatively, a sacrificial section of a column can be used. Such a sacrificial column, which is typically referred to as either a “retention gap”, “pre-column,” or a “guard column,” can be either user created (e.g., using cut pieces of deactivated fused silica capillary along with column connections), or purchased as a complete product. Still alternatively, the column may be backflushed to remove sample components that are not of analytical interest and that are slow moving in the column at the analysis temperature.
Many of the above-noted solutions require the user to handle a fused silica capillary to trap the contaminants. The capillary must be carefully installed into the inlet for the GC system to work properly. Steps of a proper installation include trimming the capillary to the required length while creating a clean, square end on it; avoiding or eliminating contamination of the inside or outside of the capillary; positioning the capillary at the correct depth into the inlet; creating a leak tight seal to the capillary; and creating a leak tight seal to the inlet. As can be appreciated, the complexity of installing the capillary after, for example, trimming the column, and the ultimate quality of the connection of the capillary to the inlet can be less than desirable or acceptable.
What is needed, therefore, is an apparatus that overcomes at least the shortcomings of known structures described above.